2,534 research outputs found
Worldsheet instantons and (0,2) linear models
We study the stability of heterotic compactifications described by (0,2)
gauged linear sigma models with respect to worldsheet instanton corrections to
the space-time superpotential following the work of Beasley and Witten. We show
that generic models elude the vanishing theorem proved there, and may not
determine supersymmetric heterotic vacua. We then construct a subclass of
linear models for which a vanishing theorem holds, generating an extensive list
of consistent heterotic backgrounds.Comment: 21 pages; v2: minor correction
Special Lagrangian torus fibrations of complete intersection Calabi-Yau manifolds: a geometric conjecture
For complete intersection Calabi-Yau manifolds in toric varieties, Gross and
Haase-Zharkov have given a conjectural combinatorial description of the special
Lagrangian torus fibrations whose existence was predicted by Strominger, Yau
and Zaslow. We present a geometric version of this construction, generalizing
an earlier conjecture of the first author.Comment: 23 pagers, 10 figure
Heterotic String Corrections from the Dual Type II String
We introduce a method of using the a dual type IIA string to compute
alpha'-corrections to the moduli space of heterotic string compactifications.
In particular we study the hypermultiplet moduli space of a heterotic string on
a K3 surface. One application of this machinery shows that type IIB strings
compactified on a Calabi-Yau space suffer from worldsheet instantons, spacetime
instantons and, in addition, "mixed" instantons which in a sense are both
worldsheet and spacetime. As another application we look at the hyperkaehler
limit of the moduli space in which the K3 surface becomes an ALE space. This is
a variant of the "geometric engineering" method used for vector multiplet
moduli space and should be applicable to a wide range of examples. In
particular we reproduce Sen and Witten's result for the heterotic string on an
A1 singularity and a trivial bundle and generalize this to a collection of E8
point-like instantons on an ALE space.Comment: 21 pages, 5 figures, refs adde
- …